Changes in fetal thyroid hormone levels in adrenalectomized fetal sheep following continuous cortisol infusion 72 h before delivery

Sensky, P. L.; Roy, Chandrima; Barnes, Richard; Heath, M. F.

doi:10.1677/joe.0.1400079

Cited by 11 publications

(5 citation statements)

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“…Cortisol can increase fetal systemic arterial pressure via AII (Forhead et al 2000), in which case the typical cardiomyocyte enlargement and maturation growth response to elevated cardiac load ensues (Lumbers et al 2005). This higher level of cortisol also increases fetal T 3 levels (Sensky et al 1994), which may suppress cardiomyocyte proliferation in the context of elevated pressure.…”

Section: Regulatory Signals Associated With Birthmentioning

confidence: 97%

Endocrine and other physiologic modulators of perinatal cardiomyocyte endowment

Jonker¹,

Louey²

2015

Journal of Endocrinology

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Immature contractile cardiomyocytes proliferate to rapidly increase cell number, establishing cardiomyocyte endowment in the perinatal period. Developmental changes in cellular maturation, size and attrition further contribute to cardiac anatomy. These physiological processes occur concomitant with a changing hormonal environment as the fetus prepares itself for the transition to extrauterine life. There are complex interactions between endocrine, hemodynamic and nutritional regulators of cardiac development. Birth has been long assumed to be the trigger for major differences between the fetal and postnatal cardiomyocyte growth patterns, but investigations in normally growing sheep and rodents suggest this may not be entirely true; in sheep, these differences are initiated before birth, while in rodents they occur after birth. The aim of this review is to draw together our understanding of the temporal regulation of these signals and cardiomyocyte responses relative to birth. Further, we consider how these dynamics are altered in stressed and suboptimal intrauterine environments.

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Section: Regulatory Signals Associated With Birthmentioning

confidence: 97%

Endocrine and other physiologic modulators of perinatal cardiomyocyte endowment

Jonker¹,

Louey²

2015

Journal of Endocrinology

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“…The pre-partum cortisol rise is accompanied by an increase in foetal T3 and a decrease in rT3 concentrations (Sensky et al, 1994). This pattern should be maintained throughout the early postnatal life (Nathanielsz et al, 1973; Klein et al, 1978).…”

Section: Gender Effectsmentioning

confidence: 98%

Thyroid hormones in small ruminants: effects of endogenous, environmental and nutritional factors

Todini

2007

Animal

193

142

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Appropriate thyroid gland function and thyroid hormone activity are considered crucial to sustain the productive performance in domestic animals (growth, milk or hair fibre production). Changes of blood thyroid hormone concentrations are an indirect measure of the changes in thyroid gland activity and circulating thyroid hormones can be considered as indicators of the metabolic and nutritional status of the animals. Thyroid hormones play a pivotal role in the mechanisms permitting the animals to live and breed in the surrounding environment. Variations in hormone bioactivity allow the animals to adapt their metabolic balance to different environmental conditions, changes in nutrient requirements and availability, and to homeorhetic changes during different physiological stages. This is particularly important in the free-ranging and grazing animals, such as traditionally reared small ruminants, whose main physiological functions (feed intake, reproduction, hair growth) are markedly seasonal. Many investigations dealt with the involvement of thyroid hormones in the expression of endogenous seasonal rhythms, such as reproduction and hair growth cycles in fibre-producing (wool, mohair, cashmere) sheep and goats. Important knowledge about the pattern of thyroid hormone metabolism and their role in ontogenetic development has been obtained from studies in the ovine foetus and in the newborn. Many endogenous (breed, age, gender, physiological state) and environmental factors (climate, season, with a primary role of nutrition) are able to affect thyroid activity and hormone concentrations in blood, acting at the level of hypothalamus, pituitary and/or thyroid gland, as well as on peripheral monodeiodination. Knowledge on such topics mirror physiological changes and possibly allows the monitoring and manipulation of thyroid physiology, in order to improve animal health, welfare and production.Keywords: goats, nutrition, seasons, sheep, thyroid hormones IntroductionAppropriate thyroid gland function and activity of thyroid hormones (TH) are considered crucial to sustain the productive performance in domestic animals (growth, milk, hair fibre production) and circulating TH can be considered as indicators of the metabolic and nutritional status of the animals (Riis and Madsen, 1985;Todini et al., 2007). Changes of blood TH concentrations are an indirect measure of the changes in thyroid gland activity. Many papers report marked seasonal variation in thyroid activity and in blood TH concentration. These hormone variations are particularly important in the free-ranging and grazing animals, whose main physiological functions (feed intake, reproduction, hair growth) are markedly seasonal. This is the case of small ruminants traditionally reared. Such variations in hormone concentration, in fact, allow the animals to adapt their metabolic balance to different environmental conditions, variations in nutrient requirements and availability, and to homeoretic changes during different physiological stages.The present paper aims to re...

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“…In part, these ontogenic changes reflect alterations in the set point and sensitivity of the endocrine axes, particularly of the HPA axis, which initiate the onset of labour and are essential for neonatal survival in most species (see Silver, 1990). Indeed, the cortisol surge towards term is responsible for the ontogenic increases in the plasma concentrations of T 3 , leptin, IGF‐I and adrenaline in the sheep fetus (Sensky et al 1994; Li et al 1996; Forhead et al 2002 b ; Fowden & Forhead, 2007). Ontogenic changes in hormones, such as leptin, are also an index of the rising fetal adiposity essential for a successful transition from parenteral to enteral nutrition at birth (Forhead & Fowden, 2009).…”

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confidence: 99%

Hormones as epigenetic signals in developmental programming

Fowden

Forhead

2009

Experimental Physiology

114

120

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In mammals, including man, epidemiological and experimental studies have shown that a range of environmental factors acting during critical periods of early development can alter adult phenotype. Hormones have an important role in these epigenetic modifications and can signal the type, severity and duration of the environmental cue to the developing feto-placental tissues. They affect development of these tissues both directly and indirectly by changes in placental phenotype. They act to alter gene expression, hence the protein abundance in a wide range of different tissues, which has functional consequences for many physiological systems both before and after birth. By producing an epigenome specific to the prevailing condition in utero, hormones act as epigenetic signals in developmental programming, with important implications for adult health and disease. This review examines the role of hormones as epigenetic signals by considering their responses to environmental cues, their effects on phenotypical development and the molecular mechanisms by which they programme feto-placental development, with particular emphasis on the glucocorticoids.

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Changes in fetal thyroid hormone levels in adrenalectomized fetal sheep following continuous cortisol infusion 72 h before delivery

Cited by 11 publications

References 0 publications

Endocrine and other physiologic modulators of perinatal cardiomyocyte endowment

Endocrine and other physiologic modulators of perinatal cardiomyocyte endowment

Thyroid hormones in small ruminants: effects of endogenous, environmental and nutritional factors

Hormones as epigenetic signals in developmental programming

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